Composite Laminates Having Hole Patterns Produced by Controlled Fiber Placement

Abstract

A composite laminate has a pattern of holes therein. The holes are formed by laying down plies of unidirectional pre-preg material having varying fiber orientations. The tows are spaced apart and located to form holes through the laminate.

What is claimed is: 
     
         1 . A method of producing a composite laminate having a pattern of holes therein, comprising:
 forming a layup by laying up multiple plies of fiber reinforced resin, each of the plies having a fiber orientation and including multiple fiber reinforced resin tows having gaps therebetween;   and   varying the fiber orientations of the plies in the layup to form a pattern of holes in the composite laminate.   
     
     
         2 . The method of  claim 1 , further comprising:
 controlling the gaps between the tows of each of the plies.   
     
     
         3 . The method of  claim 1 , wherein laying up the multiple plies includes using tows having at least two differing widths respectively in at least two of the plies. 
     
     
         4 . The method of  claim 1 , wherein laying up the multiple plies is performed automatically by a numerically controlled fiber placement machine. 
     
     
         5 . The method of  claim 1 , further comprising:
 embedding at least one of a woven and a non-woven material within the multiple plies.   
     
     
         6 . The method of  claim 1 , further comprising:
 selecting a hole pattern; and   programming an automatic fiber placement machine to automatically lay up the plies using spaced apart tows and to vary the fiber orientations of the plies to form the selected hole pattern.   
     
     
         7 . The method of  claim 6 , further comprising:
 selecting a hole size and shape; and   programming the automatic fiber placement machine to automatically lay up the plies and vary the fiber orientations of the plies to form holes having the selected hole size and shape.   
     
     
         8 . The method of  claim 1 , further comprising:
 curing the layup; and   selecting a resin having a controlled flow characteristic that substantially prevents the resin from filling in the holes during the curing.   
     
     
         9 . The method of  claim 8 , wherein curing the layup is performed using one of an out-of-autoclave and an autoclave curing process. 
     
     
         10 . A method of producing a composite laminate layup having pattern of holes therein, comprising:
 forming a layup by laying up multiple plies of unidirectional pre-preg fiber, each of the plies being laid up by laying down bandwidths of pre-preg fiber tows;   spacing the tows in each of the bandwidths apart from each other to form gaps between the tows as the bandwidths are being laid down;   controlling locations of the tows as the bandwidths are being laid down;   controlling the gaps between the tows as the bandwidths are being laid down; and   varying fiber orientations of the plies to form a pattern of holes in the layup.   
     
     
         11 . The method of  claim 10 , wherein each of the plies is laid up using a numerically controlled automatic fiber placement machine. 
     
     
         12 . The method of  claim 10 , wherein spacing the tows includes varying the gaps between the tows. 
     
     
         13 . The method of  claim 10 , further comprising varying a width of the tows. 
     
     
         14 . The method of  claim 10 , further comprising:
 embedding at least one of a woven and a non-woven material within the plies of the layup.   
     
     
         15 . The method of  claim 10 , further comprising:
 selecting hole locations, hole sizes and hole shapes; and   programming an automatic fiber placement machine to automatically lay up the plies and vary the fiber orientations of the plies to form the pattern of holes.   
     
     
         16 . The method of  claim 10 , further comprising:
 curing the layup; and   selecting a resin having a controlled flow characteristic that substantially prevents the resin from filling in the holes during the curing.   
     
     
         17 . A composite laminate having a pattern of holes therein, comprising:
 a plurality of spaced-apart fiber tows having varying fiber orientations arranged to form a pattern of holes in the laminate; and   a resin matrix in which the fiber tows are embedded.   
     
     
         18 . The composite laminate of  claim 17 , wherein fiber tows are arranged in a plurality of plies having differing fiber orientations. 
     
     
         19 . The composite laminate of  claim 17 , wherein the fiber tows have varying widths. 
     
     
         20 . The composite laminate of  claim 17 , wherein the holes each have a polygonal shape. 
     
     
         21 . The composite laminate of  claim 17 , wherein resin matrix is a thermally curable thermoset material and possesses a flow characteristic that prevents the thermoset material from flowing into the holes during thermal curing. 
     
     
         22 . A composite laminate layup containing a pattern of holes therein, comprising:
 a plurality of plies of fiber reinforced resin, each of the plies having a unidirectional fiber orientation and including multiple pre-preg tows having gaps therebetween; and   the plies being arranged such that the gaps between the pre-preg tows form a pattern of holes in the layup.   
     
     
         23 . The composite laminate layup of  claim 22 , wherein the resin is thermally curable and has flow characteristics during curing that prevent the resin from flowing into the holes. 
     
     
         24 . The composite laminate of  claim 22 , wherein the gaps between the pre-preg tows vary. 
     
     
         25 . The composite laminate of  claim 22 , wherein each of the tows has a width, and the width of the tows varies from ply to ply.